<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>INDEX</title>
</head>
<body>
    <input type="button" value="Sayhello" id="HelloBtn"/>
    <script>
        window.onload = function (){
            let BtnObj = document.getElementById("HelloBtn");
            BtnObj.onclick = function (){
                alert("hello AJAX");
            }
        }
    </script>
</body>
</html>
